1. Field of the Invention
This invention relates generally to the field of articulation devices, and more particularly to the use of articulation devices to treat disorders of the human cardiovascular system.
2. Discussion of the Related Art
Cardiovascular diseases are a leading cause of death in the United States today. To combat this problem, which affects hundreds of thousands of people yearly, doctors and other professionals have developed a variety of procedures and apparatus to fight and treat cardiovascular disease. Percutaneous transluminal coronary angioplasty and atherectomy are two common, minimally invasive procedures used today. In many instances, such relatively non-invasive procedures are considered to be preferable over more invasive procedures. More invasive procedures, such as open-heart surgery, are more traumatic to the patient and require a longer recuperation period.
Another treatment for cardiovascular disease that may be performed in a relatively non-invasive manner is transmyocardial revascularization (TMR). During this procedure, holes are formed in the heart wall to provide alternative blood flow channels for ischemic heart tissue. These holes may be formed by piercing, or alternatively may be cut by a laser. The laser energy may be directed from inside the heart to form a bore through a wall of the heart. Alternatively, a lasing apparatus may be introduced intravenously through a patient's body and into contact with a pre-selected position along the outer wall of the heart.
One approach to laser myocardial revascularization is disclosed in U.S. Pat. Nos. 5,380,316 and 5,389,096, to Aita et al. These references disclose using a deflectable elongated flexible lasing apparatus which is either introduced through a patient's vasculature or alternatively, directly into the patient's chest cavity. However, neither of these references discloses a highly flexible tip that may be controlled with an increased degree of accuracy.
U.S. Pat. No. 4,911,148, to Sosnowski et al. (the “'148 Patent”) discloses a deflectable end endoscope with a detachable flexible shaft assembly. The deflectable end segment of the endoscope is equipped with a series of discreet, substantially aligned cutouts. The cutouts are aligned such that they extend along one side of the deflectable end segment of the shaft assembly. While the cutouts provide for increased flexibility of the end segment, the configuration of the invention of the '148 patent does not provide a sufficiently even bend radius. Such bending characteristics are believed to be extremely helpful in properly locating and positioning the apparatus.
The deflectable end segment of the '148 patent may be deflected by pulling on, or otherwise shortening, a control element that is associated with the deflectable end. The imaging fiber associated with the endoscope and the tubing of the deflectable end segment provide sufficient stiffness such that, once the force on the control element is released, they act to straighten the deflected end segment from its deflected configuration. While this mechanism may work with some degree of accuracy, it is desirable to have more control over the end segment when it is straightening. That is, a control element that could function to push, as well as pull, the deflectable end segment is desirable.
The deflectable end segment of the '148 patent is equipped with a plurality of lumens extending through the tubing wall along the length of the deflectable end segment. One drawback associated with such a configuration is that fabrication of plastic elements with holes whose length exceeds more than 10 times their diameter is exceedingly difficult. Typically, the length of a lumen associated with endoscopes such as the endoscope of the '148 patent is roughly 25 to 30 times their diameter. The cost and complications associated with manufacturing such a deflectable end segment are significant, and therefore undesirable.
Clearly, there is a need for a medical articulation device having a controllable, flexible tip that may be easily manufactured, and which may have particular use in connection with performing TMR procedures.